The sweet symphony of a well-tuned lawn mower is a summer soundtrack many enjoy. But when that familiar roar turns into a sputtering cough, it can quickly dampen the spirits of even the most seasoned gardener. A common culprit for a lawnmower’s lackluster performance is a faulty ignition coil. This small but essential component is responsible for delivering the spark that ignites the fuel-air mixture, bringing your mower back to life.
But fear not! Even if you’re not a seasoned mechanic, you can diagnose a faulty coil yourself using a trusty multimeter. This article will guide you through the process, helping you pinpoint the problem and get your mower running smoothly again. We’ll cover everything from understanding the coil’s role to performing the multimeter test, and even offer some troubleshooting tips for when the coil does need replacing.
What is an Ignition Coil and How Does it Work?
An ignition coil is a crucial part of your lawnmower’s ignition system. It transforms low-voltage electricity from your battery into high-voltage electricity, creating the spark needed to ignite the fuel-air mixture in your engine’s combustion chamber. Think of it as a miniature transformer that boosts the voltage to a level powerful enough to jump the gap between the spark plug electrodes.
H2: Signs of a Faulty Ignition Coil
Before diving into the multimeter test, let’s look at the telltale signs of a failing ignition coil. These symptoms can help you narrow down the problem and confirm if the coil is indeed the culprit:
- Engine won’t start: If your lawnmower simply refuses to fire up, a faulty ignition coil is a strong possibility. The coil’s failure to deliver a spark will prevent the fuel-air mixture from igniting, making it impossible to start the engine.
- Engine starts but runs poorly: If the engine starts but sputters, misfires, or struggles to maintain a consistent idle, a malfunctioning coil could be the reason. The weak or intermittent spark produced by a failing coil can result in erratic engine performance.
- Engine dies after starting: A similar problem to the above, this indicates a failing coil intermittently delivering spark, causing the engine to stall.
- Backfiring: While backfiring can have other causes, a faulty coil can sometimes lead to this issue. The erratic spark can cause an explosion within the exhaust system, resulting in a backfire.
- Spark plug not getting spark: If you are able to remove and test the spark plug, and it is not getting spark, a failing coil is likely the culprit.
H2: Gathering Your Tools
Before we start testing, make sure you have the following:
- Multimeter: The heart of the diagnostic process. Choose a digital multimeter with both AC and DC voltage settings, as well as resistance and continuity testing capabilities.
- Safety glasses: Always protect your eyes when working with tools and electrical components.
- Gloves: Protect your hands from potential electrical shocks and grease.
- Wrench or socket: To remove the spark plug (if applicable).
- Wire diagram (optional): A diagram can be helpful for identifying the correct coil wires if you’re not sure.
H2: Preparing for the Test
- Safety First: Disconnect the spark plug wire from the spark plug before proceeding. This is essential for safety and will prevent accidental sparking that could harm you or damage your components.
- Location of the Ignition Coil: The ignition coil is typically located near the spark plug, often mounted directly to the engine block or on a separate bracket. It will be a small cylindrical or rectangular device with a wire running to the spark plug and another wire coming from the ignition system.
- Setting the Multimeter: Start by selecting the “resistance” setting on your multimeter. Most multimeters will have an “Ohms” symbol (Ω) for this setting.
H2: Performing the Test
Now that you’re prepared, let’s perform the actual test:
- Identify the Coil Terminals: Your ignition coil will have multiple terminals, usually two or three. They may be labeled or easily identifiable by color.
- Connect the Multimeter Leads: Connect the black lead of your multimeter to a known good ground point on the engine. The red lead will be used to test the coil terminals.
- Testing the Primary Winding: Locate the terminals connected to the battery (primary winding). This will be the wire coming from the ignition system to the coil. Connect your red lead to each of these terminals one at a time. A healthy ignition coil should register a resistance reading between 0.5 and 5 ohms.
- If the multimeter reads “OL” (overload) or infinity, the primary winding is likely open or broken.
- If the multimeter reads zero ohms, the primary winding is shorted.
- Testing the Secondary Winding: Locate the terminal connected to the spark plug wire (secondary winding). Connect your red lead to this terminal. You should read a resistance between 5,000 and 20,000 ohms (5 – 20 kilohms).
- If you read zero ohms, the secondary winding is shorted.
- If you read “OL” or infinity, the secondary winding is open.
H3: Interpreting the Test Results
- Normal Readings: If the resistance readings fall within the ranges mentioned above, your ignition coil is likely functioning correctly.
- Abnormal Readings: If the multimeter readings fall outside the acceptable ranges, it strongly suggests that your ignition coil is faulty and needs to be replaced.
H2: Troubleshooting a Faulty Ignition Coil
If your test reveals a faulty ignition coil, you’ll need to replace it. Here are some additional tips for troubleshooting and replacement:
- Check for Loose Connections: Before replacing the coil, ensure that all connections are tight and free of corrosion. Loose connections can mimic the symptoms of a faulty coil.
- Inspect the Spark Plug Wire: If the spark plug wire is cracked, damaged, or showing signs of wear, replace it as well. A damaged wire can prevent a spark from reaching the spark plug, even with a healthy coil.
- Replace the Ignition Coil: Once you’ve confirmed a faulty coil, it’s time for a replacement. Make sure to purchase a coil specifically designed for your mower model. Consult your owner’s manual or contact a local parts supplier for assistance in selecting the correct part.
- Installation: Installation typically involves removing the old coil, connecting the new coil to the spark plug and ignition wires, and securing it in its designated location.
H2: Tips for Avoiding Future Coil Problems
Here are some things you can do to help extend the life of your ignition coil:
- Regular Maintenance: Perform regular maintenance on your lawnmower, including cleaning, inspecting, and adjusting components as needed.
- High-Quality Fuel: Use fresh, high-quality fuel that is free of moisture and impurities. Water contamination can lead to corrosion and damage to electrical components.
- Avoid Overheating: Allow your mower to cool down after use. Excessive heat can shorten the lifespan of electrical components like the ignition coil.
Conclusion
With a little patience and the right tools, testing your lawnmower’s ignition coil is a straightforward process. By understanding how to use a multimeter and interpreting the results, you can diagnose a faulty coil and get your mower back in working order. Remember to always prioritize safety and work with caution when dealing with electrical components. If you’re unsure about any of the steps or have concerns about your electrical system, consult a qualified mechanic for assistance.
FAQ
Q1: Why would my lawnmower coil need to be tested?
The ignition coil is a critical component in your lawnmower’s ignition system. It transforms the low-voltage current from your battery into a high-voltage spark that ignites the fuel mixture in the engine cylinder. If the coil is faulty, it can prevent your lawnmower from starting or cause it to run poorly. A simple test with a multimeter can help you determine if the coil is the culprit.
You should test your coil if you are experiencing starting issues, misfiring, or other performance problems. A faulty coil can manifest in various ways, including slow starts, sputtering, stalling, or a complete lack of ignition.
Q2: What tools do I need to test my lawnmower coil?
The only tool you need to test a lawnmower coil is a multimeter. A multimeter is a versatile tool used to measure various electrical properties, including voltage, current, and resistance. You can purchase a basic digital multimeter from any hardware store or online retailer for under $20.
Make sure you select a multimeter with a continuity or resistance testing function. You will also need to have a basic understanding of how to operate the multimeter and how to interpret its readings. You can find helpful instructions and tutorials online.
Q3: Where is the ignition coil located on my lawnmower?
The location of the ignition coil can vary slightly depending on the model of your lawnmower. However, it is usually located near the spark plug and connected to it by a high-voltage wire.
Take a moment to look at your lawnmower’s engine. It is a small, cylindrical component with a wire coming out of it that connects to the spark plug. Sometimes it’s attached to the engine’s mounting plate or directly to the engine block. If you are unsure, refer to your lawnmower’s owner’s manual or search online for your model.
Q4: How do I test the lawnmower coil with a multimeter?
Testing the coil involves checking its resistance using the multimeter’s resistance setting (usually symbolized by an Ohm symbol). First, disconnect the wire leading from the coil to the spark plug. Then, set the multimeter to the appropriate resistance range, typically between 10-20 kilo-ohms.
Next, touch the multimeter probes to the coil’s terminals, one on each. A reading within the specified range indicates that the coil is working properly. If the reading is zero or outside the range, the coil might be faulty.
Q5: What do the multimeter readings mean?
The readings on the multimeter will indicate whether the coil is working properly or not. A reading within the specified range for your particular coil model (usually found in your owner’s manual) means the coil is functioning correctly.
If the reading is outside this range or reads zero, it means the coil is likely faulty and needs to be replaced. This could be due to a broken wire, short circuit, or other internal failure.
Q6: What should I do if the coil test fails?
If your coil test indicates a faulty coil, you’ll need to replace it. The good news is that ignition coils are relatively inexpensive and easy to replace.
You can buy a replacement coil online or at your local hardware store. Make sure to purchase a coil that is compatible with your specific lawnmower model. Replacing the coil is usually a simple process, and you can find instructions online or in your owner’s manual.
Q7: Can I fix a faulty lawnmower coil?
Unfortunately, fixing a faulty lawnmower coil is usually not possible. The internal components of the coil are delicate and susceptible to damage.
If the coil fails the test, the best course of action is to replace it with a new one. This will ensure that your lawnmower’s ignition system is working properly and that you can enjoy your lawn mowing experience without any issues.